New Ways of Looking at Things

It is often refreshing and surprisingly useful to research topics that you had previously overlooked. In this issue gas discharges come under the spotlight. We include papers that describe how gas discharges and plasmas may be analysed, and also a paper (refer to p. 56) that shows how gas discharges (sparks) can be used for generating very high energy acoustic pulses for use underwater for sub-bottom profiling. We also see how algorithms derived from the world of image processing have been used for removing noise from electric discharge data (refer to p. 41) and how this same filtering procedure can be applied to a very wide range of data acquisition problems.

Every now and then a new area of technology opens up and you immediately know that it is destined to have a profound impact. Lasers are one example and they in turn have led to the development of the entirely new field of Terahertz or T-ray imaging (refer to p. 20). Terahertz refers to a band in the electromagnetic spectrum that lies between infrared and radio. Just as X-rays have a shorter wavelength than visible light, T-rays wavelengths are longer. This area of the spectrum has always been there of course, but until recently it has been difficult and very expensive to actually generate T-rays, and so they have remained very much in a technology backwater.

Lasers are key to this new development as T-rays are produced by firing a near-IR laser pulse...